By mimicking the essential process that allows plants to produce energy, an MIT researcher has managed to create electricity out of water more efficiently than conventional solar cells, to the point where one and a half bottles of wastewater could power an entire house for a day.
Plants, being extremely clever, somehow manage to use sunlight to crack water into oxygen and hydrogen. They combine the hydrogen with carbon dioxide to make sugar (which is what I would do, 'cause sugar is good stuff), but we humans have been trying to figure out for about a century how to skip the sugar step and just recombine that oxygen and hydrogen back into water to generate electricity.
Daniel Nocera, a chemistry and engineering researcher at MIT, has come up with an artificial "leaf" that uses cobalt and phosphate to split water molecules using nothing but sunlight. When the oxygen and hydrogen are recombined, they make electricity at an efficiency higher than that of traditional solar cells, and it's easy to just store the gases to be recombined later in a fuel cell when the sun doesn't happen to be shining.
Nocera has just teamed up with Tata Group to work towards commercializing this technology. By sometime next year, the goal is to have a cheap power plant about the size of a refrigerator that could generate enough power with some sun and a bottle and a half of water (wastewater, even) to power a small home for a day. And it only scales up from there, apparently:
"Nocera estimates that the world consumes 14 terawatts (TW) of power today. By 2050, it will need 16TW. If his solution works, said Nocera, it would need a swimming pool full of water every day to meet the world's electricity needs."
While I'd really like to believe that, I'm not entirely sure how you get from one and a half bottles of water per house to a swimming pool for the entire planet short of using antimatter. Hmm, maybe that's the secret that plants have been hiding for a billion years.